Electrolytic cell with mercury cathode



March 13, 1951 R. M. R. ORNHJELM ELECTROLYTIC CELL WITH MERCURY CATHODEFiled Oct. 6, 1947 IN VE N TOR PuA/HR MFIUE/ TZ )QHFHEL sso/v QQNHJELMHTTOQNEX Patented Mar. 13, 1951 r,

ELECTROLYTIC CELL WITH MERCURY CATHODE Runar Mauritz Rafaelssonfirnhjclm, Kuusankoski, Finland, assignor to Kymin Osakeyhtiii- KymmeneAktiebolag, Kuusankoski, Finland Application October 6, 1947, Serial No.778,136

In Finland ctober22, 1945 Section uremic Law 690, August 8, 1946 Patentexpires October 22, 1965 3Claims. (cram- 250) I The method ofconstructing electrolytic cells with mercury cathodes from rolledsection iron is previously known. As the cell is generally troughshaped, U or I-shaped balks are mostly used. In the event that verylarge cells are constructed they may comprise a separate bottom partwith upright walls attached in a convenient manner to'the edges of thesaid bottom.

It is likewise previously known that the walls of such cells are linedwith a chlorine gas resistant material such as rubber, artificial resinor plastics, acid proof enamel, or some other substance convenient forthat purpose, and that the bottom of the cells is unlined because it iscovered with a mercury film. i

It is essential that this film of mercury, although covering the unlinedbottom of the cell completely, be as thin as possible thus savingconsiderable quantities of mercury.

The main defects of the present cells constructed of rolled sectionironare, firstly that during usage, when there isa certain consumption ofmercury, bare regions appear on the bottom of the cell. In order thatthe formation of 'such bare regions be prevented the mercury film thatis used as a cathode must be kept unnecessarily thick which, again, isuneconomic. This, however, is inevitable because otherwise hydrogen gaswill develop on the bare regions resulting in a possible explosion.Furthermore, the bottom of the cell will corrode in the said bareplaces. The second notable defect is thatthe flowing speed of mercury inthe present cells decreases at the edge between the bottom and theupright walls which decrease causes solid sodium amalgam to form at theedges of the mercury film during the electrolytic action. The saidamalgam then begins to decompose and forms hydrogen gas. This amalgamcoating also causes an accumulation of carbon particles and otherimpurities which render the circulation of mercury more difficult. Allthese disturbances in the usage of the cell make it necessary to takethe cell apart for cleaning. The aforementioned defects can be regardedas very great especially when large cells of for example '10 to 12meters in length are used, the strength of the current being 10,000to20,000 amperes, because the. said disturbances may cause seriousaccidents and injuries. To prevent this the bottoms of the describedcells are completely covered with a rubber coating through which thenecessary electrodes are passed. This bottom coating is not verylasting, however, and thus a cell/ of the said type has proved to beuneconomic.

, The object of this invention is to eliminate the'said defects evenwhen thelargest type'bf barebottomed cells are used. The invention isbased on the observation that the reason for the aforementioneddisturbances lies therein that .the bottom of a cell manufacturedfrom-rolled section iron is never completely level but "always justenough curved or-bent to necessitate the use of too much mercury becausea theoretically sufficient thin film does not cover the bottom of thecell due to the great cohesive hold of the liquid, which fact has notpreviously been-taken into consideration when constructing cells; It hasalso been observed that the decrease in-the flowing speed of mercury isdue to the; fact that the edge between cell bottom and walls that aremanufactured by the rolling process is rounded.

Furthermore similar disturbances have been observed even in the smallestangles and uneven surfaces resulting from the rolling process. Contraryto previous beliefs the originators of the disturbances that haveoccurred when cells manufactured by the rolling process have beenreplanedare continually the faults in the form of the cell. v

In conformity with the invention the described disadvantage iseliminated by accurate machining of the shaped plate, from which therespective cell bottom is made, so that the upper. surface is planed toan absolute level. Likewise the edge between bottom and walls ismachined to right.

rounded edge is eliminated.- I

An accurately machined bottom surface effects a considerable saving'ofmercury because the thickness ofthe mercury -film' in the invented cellunder reference can be kept even and so thin that the bottom of the-cellis just merely covered su fiiciently. The degree angle -between thewalls and the bottom guarantees that no disturbing amalgams'c anformulate at-that region and also that thesaid region does -not becomeuncovered. 4

In conformity with an especially favorable modification of the saidinvention the edges of the bottom that touch the sidewalls; may beequipped with an encircling channel-or trough angles with a fullydeveloped edge, i. e. -.the

which can be made by conveniently machining the respective edges of theshaped bottom plate. By this measure an even more effective means ofpreventing the edge-surface of the mercuryfilm from developing harmfulphenomena. is gained because the mercury flows with greater speed v atthe'edges than on otherregionsof thebottom surface.

formed of material impervious to the decomposition products ofelectrolyte, said lining being secured to and covering said side wallsand including a lower edge portion turned into and terminating withinsaid edge groove, a securing strip overlying said turned portion of saidlining, said securing strip being, received within said edge groove andhaving its upper surface lying below said machined surface.

2. An electrolytic cell with a mercury cathode comprising, a troughformed of iron, said trough being generally U-shaped in cross sectionwith the base of the u forming the bottom of the trough being accuratelymachined throughout to form an even flat upper surface, said uppersurface and the side walls of said trough extending at exact rightangles with respect to each other and said upper surface meeting theside walls of said trough at a definite edge, said machined uppersurface being grooved along its edges adjacent said side walls, saidside walls being provided on their interior surfaces with a protectivelining impervious to the decomposition products of electrolyte, thelower end section of said lining extending down below said machinedbottom surface of said cell and being turned to terminate in said edgegroove with the upper surface of the turned portion of said protectivelining lying below said machined upper surface of said bottom, and asecuring strip seated insaid groove to overlie said turned portion ofsaid protective lining, said strip wholly covering said turned portionand securing said turned portion in place in said groove with the uppersurface of said securing strip extending no higher than said machinedsurface.

3. An electrolytic cell with a mercury cathode comprising an ironstructure, formed with a horizontally extending center web and with sidewalls extending upwardly with respect to said center 6 web, said web andsaid side walls forming a trough, the bottom of said trough beingaccurately machined throughout providing a smooth flat surface to meetsaid side walls at a definite edge, said machined surface and said sidewalls extending at right angles to each other, said machined surfacebeing, grooved along its edges adjacent said side walls, and aprotective lining of material impervious to the decomposition productsof electrolyte, said lining being secured to and covering said sidewalls, saidlining including a lower edge turned into and terminatingwithin said edge groove, a strip overlying the turned edge of saidlining and received within said groove to hold said turned edge tightlyin place in said groove, and means to secure said strip in place with nopart of the top thereof extending above the main portion of saidmachinedsurface. v RUNAR MAURITZ RAFAELSSON ('jRNHJELM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED sTATEs PATENTS Number Name Date 115,717 Dieterich June 6, 1871259,864 Johnson June 20, 1882 1,030,490 Potter June 25, 1912 1,420,211Paulus June 20, 1922 2,15%,830 Benker Apr. 18, 1939 2,316,685 GardinerApr. 13, 1943 2,334,354 Richardson Nov. 16, 1943 FOREIGN PATENTS' NumberCountry Date 21,935 Finland Aug. 29, 1947

1. AN ELECTROYLTIC CELL WITH A MERCURY CATHODE COMPRISING AN INTEGRALIRON STRUCTURE IN THE FORM OF AN I BEAM IN CROSS-SECTION WITH THE CENTERWEB OF SAID BEAM EXTENDING HORIZONTALLY, A TROUGH FORMED BY THE SAIDCENTER WEB AND THE SAID SIDE WALLS PROVIDED BY THE UPWARDLY EXTENDINGARMS OF SAID I, THE BOTTOM OF SAID TROUGH BEING ACCURATELY MACHINEDTHROUGHOUT TO PROVIDE A SMOOTH FLAT HORIZONTAL SURFACE, SAID SIDE WALLSEXTENDING AT RIGHT ANGLES WITH RESPECT TO SAID SURFACE, THE BOTTOM OFSAID TROUGH BEING FORMED WITH A GROOVE BETWEEN SAID MACHINED SURFACE ANDEACH OF SAID SIDE WALLS, A PROTECTIVE LINING FOR SAID SIDE WALLS FORMEDOF MATERIAL IMPERVIOUS TO THE DECOMPOSITION PRODUCTS OF ELECTROYTE, SIDLINING BEING SECURED TO AND COVERING SAID SIDE LWALLS AND INCLUDING ALOWER EDGE PORTION TURNED INTO AND TERMINATING WITHIN SAID EDGE GROOVE,A SECURING STRIP OVERLYING SAID TURNED PORTION OF SAID LINING, SAIDSECURING STRIP BEING RECEIVED WITHIN SAID EDGE GROOVE AND HAVING ITSUPPER SURFACE LYING BELOW SAID MACHINED SURFACE.